Optical performance monitoring (OPM) is important in future agile optical networks (AONs), in which any fiber problem may cause significant downtime and operating cost for the network infrastructure. OPM should be available for each individual device that connects to an optical fiber. Without OPM, locating faulty optical fibers would be difficult, particularly when fiber density and system complexity are high. An optical time-domain reflectometer (OTDR) is a device used for monitoring optical fibers as part of OPM. However, the typical external hand-held OTDR is bulky, energy-consuming, and expensive.